The garage is talking bollocks. The shoes are used for the handbrake, nothing more, so unless you drive around with the handbrake on there should be no wear to the shoes. Pads and disc swap on a lift is less than an hour.

Recently changed all discs and pads, rear handbrake shoes were as new but handbrake has never been exceptional from new. Spec is to adjust up to lock wheel and back off 8 teeth, adjusted mine to 5 no binding and a much better result, went through MOT just after with no problems.